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Questions and Answers
What is the common adverse effect associated with Phenobarbital?
What is the common adverse effect associated with Phenobarbital?
Which of the following is a characteristic of Phenobarbital pharmacokinetics?
Which of the following is a characteristic of Phenobarbital pharmacokinetics?
What is the mechanism of action of Phenobarbital in the CNS?
What is the mechanism of action of Phenobarbital in the CNS?
Which of the following is a contraindication for Phenobarbital use?
Which of the following is a contraindication for Phenobarbital use?
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In what type of seizures is Phenobarbital commonly used?
In what type of seizures is Phenobarbital commonly used?
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'Increases the inhibitory neurotransmitters (e.g: GABA ) and decreases the excitatory transmission' - This statement is associated with the mechanism of action of:
'Increases the inhibitory neurotransmitters (e.g: GABA ) and decreases the excitatory transmission' - This statement is associated with the mechanism of action of:
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What is the mechanism of action of benzodiazepines?
What is the mechanism of action of benzodiazepines?
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What is a common side effect of barbiturate overdose?
What is a common side effect of barbiturate overdose?
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Which barbiturate is associated with atonic and infantile spasms?
Which barbiturate is associated with atonic and infantile spasms?
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Which benzodiazepine is specifically used for absence seizures?
Which benzodiazepine is specifically used for absence seizures?
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What clinical use is associated with mephobarbital?
What clinical use is associated with mephobarbital?
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How do barbiturates affect the CNS and respiratory system during toxicity?
How do barbiturates affect the CNS and respiratory system during toxicity?
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What is the main route of excretion of Phenobarbital?
What is the main route of excretion of Phenobarbital?
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What is a common side effect associated with Phenobarbital toxicity?
What is a common side effect associated with Phenobarbital toxicity?
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How does Phenobarbital affect the brain's GABA content?
How does Phenobarbital affect the brain's GABA content?
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In CNS disorders, Phenobarbital is particularly effective against which type of seizures?
In CNS disorders, Phenobarbital is particularly effective against which type of seizures?
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What is one of the mechanisms of action of barbiturates like Phenobarbital in the brain?
What is one of the mechanisms of action of barbiturates like Phenobarbital in the brain?
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Which drug should not be given concomitantly with Phenobarbital due to its metabolism being inhibited by Phenobarbital?
Which drug should not be given concomitantly with Phenobarbital due to its metabolism being inhibited by Phenobarbital?
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Study Notes
Phenobarbital
- Mechanism of action: increases inhibitory neurotransmitters (e.g., GABA) and decreases excitatory transmission, prolongs the opening of Cl- channels, and blocks excitatory responses induced by glutamate
- Side effects: nausea, vomiting, GIT disturbances, increased appetite and weight gain, transient hair loss, hepatotoxicity, thrombocytopenia, and neural tube defects in offspring of women
- Pharmacokinetics: long-acting barbiturate, 20-45% protein-bound, low lipid solubility, and hepatic microsomal enzyme system metabolism
- Plasma half-life: 53-118 hours (adults), 60-180 hours (children and newborns)
- Uses: partial seizures and generalized tonic-clonic seizures, but little effect on absence, atonic, and infantile spasms
Benzodiazepines
Diazepam
- Mechanism of action: interacts with specific receptors on the GABAA receptor–chloride ion channel macromolecular complex
- Uses: generalized tonic-clonic and status epilepticus
- Pharmacokinetics: well-absorbed, widely distributed, extensively metabolized to many active metabolites
- Plasma binding: 95%
- Half-life: 20-40 hours
- Toxicity: sedation, drowsiness, and lethargy, strong inducing agent
Lorazepam
- Uses: status epilepticus
- Pharmacokinetics: rapidly and extensively distributed
- Plasma binding: 85%
- Half-life: 20-40 hours
Clonazepam
- Uses: absence seizures
- Pharmacokinetics: well-absorbed, widely distributed, extensively metabolized
- Plasma binding: 85%
- Half-life: 20-40 hours
Nitrazepam
- Uses: infantile spasms, myoclonic seizures
- Pharmacokinetics: well-absorbed, widely distributed, extensively metabolized
- Plasma binding: 80%
- Half-life: 20-40 hours
Clorazepate Dipotassium
- Uses: complex partial seizures
- Pharmacokinetics: well-absorbed, widely distributed, extensively metabolized
- Plasma binding: 90%
- Half-life: 20-40 hours
Carbamazepine
- Mechanism of action: interacts with voltage-gated Na+ channels, increases K+ conductance
- Pharmacokinetics: well-absorbed, widely distributed, extensively metabolized
- Plasma binding: 70-80%
- Half-life: 30 hours
- Toxicity: GI upset, drowsiness, ataxia, headache, diplopia, hepatotoxicity, congenital malformations, hyponatraemia, water intoxication, and late hypersensitivity reaction
Sodium Valproate (Valproic Acid)
- Mechanism of action: increases GABA content in the brain, attenuates Ca-mediated T current, and prolongs Na+ channel inactivation
- Pharmacokinetics: available as capsule, syrup, and IV, high oral bioavailability, inhibits metabolism of several drugs
- Plasma half-life: approximately 15 hours
- Clinical use: effective against absence, myoclonic, and generalized tonic-clonic seizures, less effective for partial seizures, and used for mania treatment
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Description
Learn about the toxicity effects of Phenobarbital, such as nausea, vomiting, weight gain, and hepatotoxicity. Understand how Phenobarbital increases inhibitory neurotransmitters and decreases excitatory transmission by prolonging the opening of Cl- channels. Explore its mechanism of action and potential neural tube defects in offspring.
